The present invention relates to a material testing machine. More specifically, the invention relates to a material testing machine that digitalizes the detection output of the test force which acts on a test piece or the amount of the deformation (extension) of the test piece by an A/D converter, and obtains these measurement data.
Generally, in a material testing machine, the load is added to the test piece by driving a load mechanism. The test force exerted on the test piece by the load is constantly detected by a load cell, or, the deformation of the test piece, for example, the extension, is constantly detected by an extensometer. From the results of the constant detection, the characteristics of the test piece are examined, or the detection values selected as the amount of the control of these detection values are fed back to a target value signal. Accordingly, the load mechanism is driven and controlled.
Usually, in this kind of material testing machine, the detection output of the test force by the load cell, or the detection output of the extension by the extensometer is digitalized by the A/D converter after being amplified respectively by an amplifier. The detected output is used for various data processing as measurement data of the test force or extension, or the feedback controls (for example, refer to Japanese Patent Unexamined Publication No. 2002-357521 and Japanese Patent Unexamined Publication No. 2004-212172).
In a conventional material testing machine, the A/D converter is provided for every multiple detection output, or, an IC for A/D conversion with multiple channels is used. Also, a device using multiplexed multiple channels is used. However, in either case, the number of channels for the A/D conversion is preset to a certain number, and cannot be changed. Moreover, the sampling rate and accuracy of each A/D converter or each channel are individually constant, and never change.
However, in the above-mentioned conventional material testing machine, the number of channels for the A/D conversion which can be inputted as a device is fixed. As a result, for example, in a material testing machine with four channels for the A/D conversion, when only one channel is used, the other three channels do not contribute to the conversion at all so that the three channels are useless.
Accordingly, in the material testing machine with multiple channels for A/D conversion of the present invention, an object of the invention is to provide a material testing machine able to be set with the maximal resource according to the use condition of a user without wasting an unused channel.
Further objects and advantages of the invention will be apparent from the following description of the invention.